Adenovirus patent awarded to Introgen

Adenoviruses have immense potential as vectors in gene therapy and vaccination as they can be genetically altered in vitro​ to code for specific proteins, without producing pathogenic viral offspring.

The patent awarded to Introgen relates to the production of purified adenoviral compositions produced on a commercial scale, and that can be readily validated for regulatory purposes. Introgen has also been selected to manufacture the worldwide adenoviral reference material, which will be used by firms and institutions developing adenovirus-based products.

"The purification technology covered by this patent is currently being employed throughout the industry by Introgen and others, and is thus recognised as an industry standard for clinical production of adenovirus."​ said David Parker, Introgen's senior vice president of intellectual property.

Introgen utilises andenoviral vectors in several of its products in various stages of clinical development, and this latest patent complements three other US patents the company has relating to the production of adenoviral vectors.

An increasingly popular line of research regarding adenoviral vectors is their application in developing new forms of vaccine. Introgen is currently applying its adenoviral vector technology to develop personalised therapeutic cancer vaccines using the dendritic cells obtained from the patient's own blood.

An adenoviral vector is used to modify the cell's genetics with a cancer-related protein, so that when the cells are reintroduced to the body they activate T-cells to seek out and destroy selected cancer proteins in the patient's body.

These dendritic cell based tumour vaccines show a great deal of potential in cancer immunotherapy, and Introgen's candidate using their cancer vaccine technology is currently in Phase I - II clinical trials.

However, although the dendritic cell vaccine and adenovirus-mediated gene therapy can both stimulate an anti-tumour immune response, they have been shown to be ineffective in combating well-established tumours in animal models. As such their current primary uses would be to inhibit the growth of small tumours, or to prevent the initial tumour cells from re-establishing themselves after treatment.

In November this year, the US Food and Drug Administration (FDA) published guidance for sponsors of gene therapy studies in response to concerns regarding delayed adverse effects in subjects who have been exposed to investigational gene therapy products.

The FDA's main concerns were regarding the use of three gene therapy vectors currently under study - Gammaretrovirus, Lentivirus and Herpesvirus. Between them these vectors pose the risk of delayed adverse effects as they have been observed to integrate with the host genome or reactivate after a period of latency.

Adenovirus and adeno-associated virus (AAV) based vectors, however, do not have the propensity to integrate or reactivate, and thus appear to present a lower risk option for gene therapy.